1. Field of the Invention
This present invention relates to query processing, and more specifically relates to techniques for facilitating the process of refining search queries.
2. Description of Related Art
With the increased growth of the Internet and the World Wide Web, it is common for on-line users to utilize search engines to search for desired information. Many web sites permit users to perform searches to identify a small number of relevant items among a much larger domain of items. As an example, several web index sites permit users to search for particular web sties among known web sites. Similarly, many on-line merchants permit users to search for particular products among all of the products that can be purchased from the merchant.
In order to perform a search, a user submits a search query containing one or more query terms. The search query may also explicitly or implicitly identify a record field or segment to be searched, such as title, author, or subject classification of the item. For example, a user of an on-line bookstore may submit a title-field-restricted search query containing terms that the user believes appear within the title of a book. A query server program of the search engine processes the search query to identify any items that match the terms of the search query. The set of items identified by the query server program is referred to as a “query result.” In the on-line bookstore example, the query result is a set of books that satisfy the query, and in the web index site example, the query result is a set of web sites or web pages. In some implementations the query result may include items that contain only a subset of the terms of the search query. In web-based implementations, the query result is typically presented to the user as a hypertextual listing of the located items.
If the scope of the search is large, the query result may contain hundreds, thousands, or even millions of items. If a user is performing the search in order to find a single item or a small set of items, conventional approaches to ordering the items within the query result often fail to place the sought item or items near the top of the query result. This deficiency often requires the user to read through many items in the query result before reaching the sought item.
Some search engines suggest related query terms to the user as part of the “search refinement” process. Through the search engine's user interface, the user can select one or more of these related terms to add to the query. The goal of this process is to produce a refined search query that more narrowly specifies the user's intended request. The related query terms can be generated by the search engine using the contents of the query result, such as by identifying the most frequently used terms within the located documents or other items.